The present invention relates to compression spring rods, and more particularly, to a spring and rod assembly that exerts an expansional force which increases at a linear rate.
The invention relates to a mechanism for biasing hoods, tops, doors, hinged covers, and other elements from a closed to an open position. The invention involves the use of springs in conjunction with a rod member to exert the driving force on the elements to be displaced. The following patents are incorporated herein by reference as background information with regard to spring mechanisms: U.S. Pat. No. 6,199,843 to DeGrace; U.S. Pat. No. 5,810,339 to Kxc3xcspert, et al.; and U.S. Pat. No. 4,962,916 to Palinkas.
Compression spring rods are used in various applications, for example, to assist in lifting, opening, and damping. Typical applications include lifting a lid hinged to a stationary base. Other applications include lifting and/or balancing elements for the trunk or hatchback of an automobile. Still another application includes a damping spring for closing a door hinged to a stationary frame. Most applications involve the use of a pneumatic or gas spring to assist the opening motion. Many of these types of compression spring assemblies contain either gas or hydraulic fluid to control forces and piston speeds. Consequently, because these products contain a gas and/or fluid, they are subject to premature failure, due to the leakage of the gas or fluid over time. The leakage results in a loss of control forces and a subsequent loss of spring life.
The present invention provides an improved compression spring rod which overcomes the above referred-to difficulties and others with regard to such rods heretofore available. More particularly in this respect, a compression spring rod in accordance with the invention is particularly adapted for lifting or pivoting one component relative to another component at a controlled rate. In accordance with one aspect, the invention provides a lift mechanism for hinged covers and the like that operates automatically upon release of the cover, or a lift mechanism for a loaded platform wherein the platform is elevated, progressively, as the load thereon is reduced. Advantageously, the compression spring assembly applies a constant and controlled force to open the cover or lift the platform. The mechanism is able to support significant loads while maintaining strength over a greater number of operating cycles than existing pneumatic or gas spring designs. Further, the invention provides a purely mechanical compression rod assembly that can yield controllable forces over a long period of use and control the spring forces during both extension and compression.
A compression spring rod according to the invention is comprised of multiple compression springs. The compression spring rod assembly includes a rod which is adapted to extend and retract relative to a housing. In one application, for example, the compression springs will build potential force as the springs are compressed, and release that force once the springs are allowed to expand. This extension of the springs imparts a force to the parts connected to the ends of the rod and housing and, advantageously, multiple end configurations can be used to adapt the spring rod to a variety of mounting applications. The compression springs of a spring rod according to the invention are interrelated to produce a linear load versus deflection curve. The encased springs minimize load losses over time, and the mechanism does not contain any fluid or gases within the lift body. This advantageously eliminates the inevitable problem of leakage and subsequent loss of utility.
It is accordingly an outstanding object of the present invention to provide an improved compression spring rod for exerting an operating force on a displaceable member at a controlled rate.
Another object of the invention is the provision of a compression spring rod that supplies a consistent force over an extended period of time and maintains strength over a greater number of cycles compared to compression spring rods heretofore available.
Yet another object of the invention is the provision of a compression spring rod having at least two compression springs interrelated to produce a linear load versus deflection curve.
Yet another object of the invention is the provision of a compression spring rod having at least two compression springs interrelated to minimize load losses over time.
A further object of the invention is the provision of a mechanical compression spring rod assembly that provides an operating force that increases at a linear rate.
Yet a further object of the invention is to provide a mechanical compression spring assembly that can accommodate, selectively, multiple end configurations, thus adapting the assembly for mounting in a wide variety of use applications.